Histological grading of oral epithelial dysplasia: revisited

The significance of Epstein Barr virus (EBV) & DNA topoisomerase II alpha (DNA-Topo II alpha) immunoreactivity in normal oral mucosa, oral epithelial dysplasia (OED) and oral squamous cell carcinoma (OSCC)

Background

Head and neck cancer including oral cancer is considered to develop by accumulated genetic alterations and the major pathway is cancerization from lesions such as intraepithelial dysplasia in oral leukoplakia and erythroplakia. The relationship of proliferation markers with the grading of dysplasia is uncertain. The involvement of EBV in oral carcinogenesis is not fully understood.

Aim

The present study was designed to investigate the role of EBV and DNA Topoisomerase II∝ (DNA-Topo II∝) during oral carcinogenesis and to examine the prognostic significance of these protein expressions in OSCCs.

Methods

Using specific antibodies for EBV and DNA-Topo II∝, we examined protein expressions in archival lesion tissues from 16 patients with oral epithelial dysplasia, 22 oral squamous cell carcinoma and 20 normal oral mucosa by immunohistochemistry. Clinical information was obtained through the computerized retrospective database from the tumor registry.

Results

DNA-Topo II∝ was expressed in all examined specimens. Analysis of Variance ANOVA revealed highly significant difference (P < 0.01) in young aged labial tissues and significant (P ≤ 0.05) in gingival and not significant (P > 0.05) in inferior surface of tongue and in hard palatal tissues. Significant differences were observed between OEDs and NSE (P < 0.001) and SCCs and controls (P < 0.001), also, significant differences could be observed between SCCs and OEDs. DNA-Topo II∝ expression was significantly higher in tumors of low differentiation versus tumors of moderate and high differentiation (P < 0.001), DNA-Topo II∝ expression was correlated with age, tumor size, tumor stage, node metastasis and tumor differentiation, but not with gender and tumor site. None of normal squamous epithelium (NSE) expressed EBV. Heterogenous reactivity for EBV was observed through the series of dysplasia and squamous cell carcinoma. Its expression increased progressively with lymph node metastasis and low tumor differentiation, but no significant association could be observed with other clinicopathological parameters. EBV protein expression was increased with elevated Topo II-∝ LI in OEDs and OSCCs. A tendency to positive correlation between EBV and Topo II∝ expression was observed in OEDs but not in OSCCs.

Conclusion

EBV and DNA Topo II-αLI expression are possible indicators in oral carcinogenesis and may be valuable diagnostic and prognostic indices in oral carcinoma.

The use of an oral brush biopsy without computer-assisted analysis in the evaluation of oral lesions: a study of 94 patients

OBJECTIVE

The objective of this study was to evaluate the sensitivity and specificity of modified brush biopsy without computer-assisted analysis in the detection of oral premalignant and malignant lesions.

STUDY DESIGN

Ninety-four patients attending outpatient clinics who exhibited oral lesions suspicious of premalignancy or malignancy were enrolled. All patients underwent an oral brush biopsy using a baby toothbrush followed by a scalpel biopsy. The specimens were analyzed manually in a double-blinded fashion. Sensitivity and specificity were used for the statistical analysis of the samples. Statistical significance was determined using the normal approximation to the binomial distribution of matched results, approximated by the Student t distribution mean test (paired t test).

RESULTS

Seventy-nine patients with adequate transepithelial brush biopsy samples were included in the study group. When compared to scalpel biopsy, the statistical sensitivity of the brush biopsy was greater than 76.8% (P < .05) while the statistical specificity was greater than 93.3% (P < .05). There were 4 false negative brush biopsy cases. The 4 false negative patients turned out to be dysplasia/ malignancy on histopathology. All 4 were patients with clinical oral submucous fibrosis.

CONCLUSION

The oral brush biopsy without computer-assisted analysis was found to be a painless, noninvasive test for evaluating oral lesions. The toothbrush brush biopsy with manual analysis had much [corrected] lower sensitivity and specificity than the commercially available oral brush biopsy with computer-assisted analysis. The results demonstrate that by using a toothbrush to obtain an oral brush biopsy sample, oral lesions can be easily evaluated in a resource challenged settings to rule out dysplasia and carcinoma.

The impact of liquid-based oral cytology on the diagnosis of oral squamous dysplasia and carcinoma

OBJECTIVE

Even though diagnostic oral exfoliative cytology is a useful, economical and practical tool in the diagnosis of oral dysplasia and carcinoma, it is not yet extensively used. The results of conventional exfoliative and liquid-based diagnostic cytology in oral potentially malignant lesions (PML) are herein reported and compared with the histological diagnosis.

METHODS

Either conventional (89) or liquid-based (384) exfoliative cytology was used for the diagnosis of oral dysplasia/carcinoma in 473 subjects and the results were compared with scalpel biopsy histology. Cells were collected using a Cytobrush device for conventional smears and with a dermatological curette for the liquid-based cytology. The 'curette technique' also allowed for the collection of 'accidental' tissue fragments, utilized as microbiopsies.

RESULTS

Histological diagnosis was squamous carcinoma in 96 of 473 cases, high-grade dysplasia (oral intraepithelial neoplasia two to three) in 24 and other lesions in 353 cases. The smears in the conventional cytology group were inadequate in 12.4%, with an 85.7% sensitivity and a 95.9% specificity. There were 8.8% of inadequate specimens in the liquid-based cytology group; sensitivity was 95.1% and specificity was 99.0%.

CONCLUSIONS

Although conventional cytology is useful when diagnosing oral PML (better sensitivity and predictive positive value if compared with the cervical smear test with similar specificity) and can improve the accuracy of histological diagnosis, liquid-based cytology gives better results, as it not only enhances both sensitivity and specificity, but also provides material for further investigation (AgNORs, DNA, microbiopsies, etc.).

Nomenclature and classification of potentially malignant disorders of the oral mucosa

At a workshop coordinated by the WHO Collaborating Centre for Oral Cancer and Precancer in the UK issues related to terminology, definitions and classification of oral precancer were discussed by an expert group. The consensus views of the Working Group are presented here. The term, 'potentially malignant disorders', was recommended to refer to precancer as it conveys that not all disorders described under this term may transform into cancer. Critically evaluating all definitions proposed so far for oral leukoplakia, the Working Group agreed that the term leukoplakia should be used to recognize 'white plaques of questionable risk having excluded (other) known diseases or disorders that carry no increased risk for cancer'. An outline was proposed for diagnosing oral leukoplakia that will prevent other oral white disorders being misclassified as leukoplakia. The Working Group discussed the caveats involved in the current use of terminology and classification of oral potentially malignant disorders, deficiencies of these complex systems, and how they have evolved over the past several decades. The terminology presented in this report reflects our best understanding of multi-step carcinogenesis in the oral mucosa, and aspires to engender consistency in use.

Factors associated with underdiagnosis from incisional biopsy of oral leukoplakic lesions

OBJECTIVES

Incisional biopsy is accepted by most clinicians as a dependable way of assessing the nature of oral leukoplakia (OL). The aim of the present study was to investigate its reliability and analyze risk factors associated with underdiagnosis from incisional biopsy.

STUDY DESIGN

A cross-sectional retrospective study was conducted in 242 patients with a clinical diagnosis of OL. The discrepancy between provisional diagnosis (from incisional biopsy) and definitive diagnosis (from resection specimen) was analyzed and correlated with clinical variables. Patients who had incisional biopsy taken from a single location and those who received multiple-site biopsies were analyzed separately.

RESULTS

In the 200 cases receiving single-site biopsy, the agreement rate between provisional and definitive diagnoses was only 56%, and underdiagnosis from incisional biopsy was noted in 29.5% of patients. Underdiagnosis rate in the 42 patients receiving multiple-site biopsies was significantly lower (11.9%; P < .05). The rate of unexpected carcinoma in resection specimen was also significantly lower in the multiple-biopsy patients than in the single-biopsy patients (2.4% vs. 12.0%; P < .05). For the single-biopsy group, multivariate analysis revealed that clinical appearance significantly influenced the risk of underdiagnosis and unexpected carcinoma (both P < .05). Compared with homogeneous lesions, nonhomogeneous OL were more prone to be underdiagnosed (adjusted odds ratio [AOR] 2.36, 95% confidence interval [CI] 1.16-4.82) and have carcinoma undetected by incisional specimen (AOR 15.94, 95% CI 2.09-121.72).

CONCLUSIONS

Incisional biopsy was found to have limitations in the assessment of OL, especially for nonhomogeneous lesions. Clinicians should be conscious of the possible underdiagnosis from incisional biopsy, and multiple biopsies should be taken whenever they think that it is necessary.

Evaluation of a new binary system of grading oral epithelial dysplasia for prediction of malignant transformation

The aim of this paper is to assess the reproducibility of a novel binary grading system (high/low risk) of oral epithelial dysplasia and to compare it with the WHO classification 2005. The accuracy of the new system for predicting malignant transformation was also assessed. Ninety-six consecutive oral epithelial dysplasia biopsies with known clinical outcomes were retrieved from the Oral Pathology archives. A pilot study was conducted on 28 cases to determine the process of classification. Four observers then reviewed the same set of H&E stained slides of 68 oral dysplastic lesions using the two grading systems blinded to the clinical outcomes. The overall inter-observer unweighted and weighted kappa agreements for the WHO grading system were Ks = 0.22 (95% CI: 0.11-0.35), Kw = 0.63 (95% CI: 0.42-0.78), respectively, versus K = 0.50 (95% CI: 0.35-0.67) for the new binary system. Interestingly, all pathologists showed satisfactory agreement on the distinction of mild dysplasia from severe dysplasia and from carcinoma in situ using the new WHO classification. However, assessment of moderate dysplasia remains problematic. The sensitivity and specificity of the new binary grading system for predicting malignant transformation in oral epithelial dysplasia were 85% and 80%, respectively and the accuracy was 82%. The new binary grading system complemented the WHO Classification 2005 and may have merit in helping clinicians to make critical clinical decisions particularly for the cases of moderate dysplasia. Histological grading of dysplasia using established criteria is a reproducible prognosticator in oral epithelial dysplasia. Furthermore, the present study showed that more consensus scoring on either the degree of dysplasia, assessment of risk or the presence of each morphological characteristic by a panel should be encouraged.

Why oral histopathology suffers inter-observer variability on grading oral epithelial dysplasia: an attempt to understand the sources of variation

The present study attempted to assess the reasons behind the inter-observer variation in grading oral epithelial dysplasia (OED). Three oral pathologists and one general pathologist examined 68 histological slides of OED lesions of variable grade for scoring the presence of each individual characteristic of the architecture and cytology changes that were established by the 2005 WHO classification. The assigned features in each case were correlated with clinical outcomes to understand which features are more commonly associated with malignant transformation. Interestingly, for all individual characteristics, the pairwise inter-examiner and group kappa values ranged from poor to moderate. It appeared that for each characteristic separately there was much dissension. Despite these observations, comparing these data with that from our previous paper on the same slides showed that the inter-observer agreement on the degree of dysplasia either by using the new binary system of "low-risk" or "high-risk" or by using the 2005 WHO classification turned out to be better than the agreement on the individual characteristics of architecture and cytology changes. Certain features show significant association with the clinical outcomes. In the discussion, some explanations to help understanding the sources of variation in grading OED are put forward. In conclusion, grading dysplasia is not an exact science and pathologists are doing their best to reach optimal results. Improvement in the standard of the histopathology reporting of OED lesions could be achieved by consideration of several issues. Of these, there is need for a universal definition of the architectural and cytological features that are the basis of any OED grading process. A minimum dataset for reporting OED lesions should be set up. Also, the use of a consensus scoring process between two or more observers should be encouraged as this would improve inter-observer agreement.

Oral submucous fibrosis: Review on aetiology and pathogenesis

Data from recent epidemiological studies provide overwhelming evidence that areca nut is the main aetiological factor for OSF. A clear dose-dependent relationship was observed for both frequency and duration of chewing areca nut (without tobacco) in the development of OSF. Commercially freeze dried products such as pan masala, Guthka and mawa (areca and lime) have high concentrates of areca nut per chew and appear to cause OSF more rapidly than by self prepared conventional betel quid that contain smaller amounts of areca nut. It is logical to hypothesise that the increased collagen synthesis or reduced collagen degradation as possible mechanisms in the development of the disease. There are numerous biological pathways involved in the above processes and, it is likely that the normal regulatory mechanisms are either down regulated or up regulated at different stages of the disease. Among the chemical constituents, alkaloids from areca nut are the most important biologically whilst tannin may have a synergistic role. These chemicals appear to interfere with the molecular processes of deposition and/or degradation of extracellular matrix molecules such as collagen. In vitro studies on human fibroblasts using areca extracts or chemically purified arecoline support the theory of fibroblastic proliferation and increased collagen formation that is also demonstrable histologically in human OSF tissues. The copper content of areca nut is high and the possible role of copper as a mediator of fibrosis is supported by the demonstration of up regulation of lysyl oxidase in OSF biopsies. It has been postulated that areca nut may also induce the development of the disease by increased levels of cytokines in the lamina propria. Increased and continuous deposition of extracellular matrix may take place as a result of disruption of the equilibrium between matrix metalloproteinases (MMPs) and tissue inhibitors of matrix metalloproteinases (TIMP). Current evidence implicates collagen-related genes in the susceptibility and pathogenesis of OSF. The individual mechanisms operating at various stages of the disease-initial, intermediate and advanced-need further study in order to propose appropriate therapeutic interventions.

Effective management of smoking in an oral dysplasia clinic in London

BACKGROUND

Precancerous lesions precede the development of oral cancer; of several clinical types the most common is leukoplakia. The risk factors include tobacco and excess alcohol use and diets low in antioxidants. Studies concerning the management of risk factors related to oral precancer are meager.

OBJECTIVES

We investigated the effectiveness of smoking cessation at a dysplasia clinic among patients followed up for at least for 12 months.

METHODS

Data from case notes relating to 180 patients with white and red patches of oral mucosa (excluding other benign disorders confirmed by biopsy findings) attending a dysplasia clinic at a teaching hospital in London and seen by one consultant between 1993 and 2003 were transcribed. Effect of referring to a smoker's clinic to receive specialist help was evaluated against brief advice given at the dysplasia clinic +/- medications.

RESULTS

The mean age at the first visit was 48.5 years (+/-12.5), 65% were male, and 88% were white European. One hundred and sixty-two patients (90%) had used tobacco and 83% were current smokers. Of the smokers 95% had smoked over 10 years, the majority smoking over 10 cigarettes per day. Nine were alcohol misusers including two binge drinkers. One hundred and forty-six were diagnosed with oral leukoplakia, 16 with non-homogeneous types (speckled or nodular). Three patients were diagnosed with an erythroplakia. Nineteen per cent exhibited the presence of dysplasia and one subject had in situ carcinoma. Five patients in the sample quit smoking prior to arrival in the dysplasia clinic. Twenty-seven cases (20%) with oral leukoplakia quit smoking while registered as a patient at the dysplasia clinic: 17 of 100 subjects quit with brief advice +/- medications and 10 of 30 following referral to the smoker's clinic. The difference between the two groups was significant for point prevalence abstinence at the last visit to the clinic (minimum 12 months follow up). Out of a total of 180 precancer cases managed in the dysplasia clinic (mean follow up 4.2 years) three patients subsequently developed invasive carcinoma during follow up.

CONCLUSIONS

Smoking cessation needs to be an integral component of management of cases attending a dysplasia clinic and referring to smoker's clinics could help to improve the effectiveness of managing patients with oral precancer to quit smoking.

Oral erythroplakia--a review

Oral erythroplakia (OE) is considered a rare potentially malignant lesion of the oral mucosa. Reports entirely devoted to OE are very few, and only two reviews none of which are of recent date have been published. Only the true, velvety, red homogeneous OE has been clearly defined while the terminology for mixed red and white lesions is complex, ill-defined and confusing. A recent case control study of OE from India reported a prevalence of 0.2%. A range of prevalences between 0.02% and 0.83% from different geographical areas has been documented. OE is predominantly seen in the middle aged and elderly. One study from India showed a female:male ratio of 1:1.04. The soft palate, the floor of the mouth and the buccal mucosa is commonly affected. A specific type of OE occurs in chutta smokers in India. Lesions of OE are typically less than 1.5 cm in diameter. The etiology of OE reveals a strong association with tobacco consumption and the use of alcohol. Histopathologically, it has been documented that in OE of the homogenous type, 51% showed invasive carcinoma, 40% carcinoma in situ and 9% mild or moderate dysplasia. Recently, genomic aberrations with DNA aneuploidy has been demonstrated. p53 mutations with different degrees of dysplasia may play a role in some cases of OE. Transformation rates are considered to be the highest among all precancerous oral lesions and conditions. Surgical excision is the treatment of choice. Data on laser excision are not available. Recurrence rates seem to be high, reliable data are, however, missing. More studies on OE are strongly needed to evaluate a number of so far unanswered questions. The natural history of OE is unknown. Do OEs develop de novo or are they developing from oral leukoplakia through several intermediate stages of white/red lesions? The possible role of fungal infection (Candida micro-organisms) is not clear as is the possible role of HPV co-infection in the development of OE. More data on incidence and prevalence, biological behaviour and adequate treatment are urgently needed.

Divergent Patterns of Allelic Alterations in Premalignant Laryngeal Lesions Indicate Differences in the Impact of Morphological Grading Characteristics

OBJECTIVES

Classic histological grading and molecular genetic analysis of epithelial hyperplastic laryngeal lesions (EHLL) were correlated in an attempt to elucidate, which classic marker reflects best the gradual progression of laryngeal premalignant lesions as determined by an increasing number of molecular genetic aberrations.

METHODS

Thirty-two EHLL were grouped according to four grades of nuclear atypia, four degrees of epithelial maturation and three groups of overall and suprabasal mitotic activity. Overall and suprabasal proliferative activity were measured by MIB-1 immunostaining and staged according to four levels. Allelic imbalance was determined by PCR using 32 microsatellite loci at nine chromosomal arms.

RESULTS

Of the six classic criteria, only progressive mitotic indices correlated with allelic alterations in a remarkable variety of microsatellite markers, especially at chromosome 17p.

CONCLUSION

Using the number of allelic alterations as standard for assessment, this preliminary study gives first evidence that certain morphological criteria could reflect differently the gradual progression of premalignant laryngeal lesions with mitotic index being the most promising marker. Further studies with long-term follow-up are required to prove the predictive value of these criteria in daily practice.

Novel management of oral cancer: a paradigm of predictive oncology

The rationale for molecular-targeted prevention of oral cancer is strong. Oral cancer is a major global threat to public health with 300,000 new cases diagnosed worldwide on an annual basis. Notably, the great morbidity and mortality rates of this devastating disease have not improved in decades. Oral cancer development is a tobacco-related multistep and multifocal process involving field carcinogenesis and intraepithelial clonal spread. Biomarkers of genomic instability, such as aneuploidy and allelic imbalance, can accurately measure the cancer risk of oral premalignant lesions or intraepithelial neoplasia (IEN). Retinoid-oral IEN studies (e.g., retinoid acid receptor-beta, p53, genetic instability, loss of heterozygosity, and cyclin D1) have advanced the overall understanding of the biology of intraepithelial carcinogenesis and preventive agent molecular mechanisms and targets, important advances for monitoring preventive interventions, assessing cancer risk, and pharmacogenomics. Clinical management of oral IEN varies from watchful waiting to complete resection, although complete resection does not prevent oral cancer in high-risk patients. New approaches, such as interventions with molecular-targeted agents and agent combinations in molecularly defined high-risk oral IEN patients, are urgently needed to reduce the devastating worldwide consequences of oral cancer.

Loss of heterozygosity at 9q33 and hypermethylation of the DBCCR1 gene in oral squamous cell carcinoma

The DBCCR1 gene at chromosome 9q33 has been identified as a candidate tumour suppressor, which is frequently targeted by promoter hypermethylation in bladder cancer. Here, we studied the possible involvement of DBCCR1 in the development of oral squamous cell carcinoma. DNA from 34 tumours was examined for loss of heterozygosity (LOH) at three markers surrounding DBCCR1 and for hypermethylation of the DBCCR1 promoter, using methylation-specific PCR and methylation-specific melting-curve analysis. LOH was found in 10 of 31 cases (32%), and DBCCR1 hypermethylation was present in 15 of 34 cases (44%). Hypermethylation of DBCCR1 was also present in three of seven epithelial tissues adjacent to the tumours, including two hyperplastic and one histologically normal epithelia. Furthermore, of four oral leukoplakias with dysplasia, one showed LOH at 9q33 and two showed DBCCR1 hypermethylation. These data suggest that LOH at 9q33 and hypermethylation of the DBCCR1 promoter are frequent and possibly early events in oral malignant development.

Quantification of the global and local complexity of the epithelial-connective tissue interface of normal, dysplastic, and neoplastic oral mucosae using digital imaging

This study aimed at quantifying the complexity of the epithelial-connective tissue interface (ECTI) in human normal mucosa, premalignant, and malignant lesions using fractal geometry. Two approaches were used to describe the complexity of 377 oral mucosa ECTI profiles. The box counting method was used to estimate their global fractal dimension, while local fractal dimensions were estimated using the mass radius relation at various local scales. The ECTI complexity significantly increased from normal through premalignant to malignant profiles in both global and local (over 283 microm) scales. Normal mucosa samples from different sites of the oral cavity also had different degrees of global complexity. Fractal geometry is a useful morphological marker of tissue complexity changes taking place during epithelial malignancy and premalignancy, and we propose it as a quantitative marker of epithelial complexity.

Architectural analysis of oral cancer, dysplastic, and normal epithelia

BACKGROUND

We present a novel, automated, and quantitative approach to evaluate local epithelial tissue architecture based on mathematical graph theory.

METHODS

Four hundred forty-one images of three diagnostic classes of oral epithelium (normal, dysplastic, and neoplastic) were analysed. The epithelial compartment was partitioned into exclusive areas associated with each nucleus to approach the theoretical cell extents. The spatial arrangement of cells in neighbourhoods of two sizes was characterised by constructing graph networks based on the cell centroids and recording 29 statistical properties. We analysed 104,627 and 67,590 neighbourhoods of diameters 37.5 and 75 microm, respectively.

RESULTS

The discrimination power of the architectural descriptors was evaluated by using discriminant analysis. The best neighbourhood discrimination rate was 75% for normal versus carcinoma. For the pooled data, discrimination into three classes based on largest number of neighbourhoods associated with each class was 100% correct. Case-wise, discrimination rates were 67%, 100%, and 80% correct for normal, premalignant, and malignant. When considering two classes, discrimination rates was 89% (normal) and 100% (malignant) correct, with 71% of premalignant cases assigned to the malignant class.

CONCLUSIONS

The results indicate that unbiased and reproducible quantification of tissue architectural features is possible and may provide valuable morphological information for diagnostic purposes.

Prognosis of oral pre-malignant lesions: significance of clinical, histopathological, and molecular biological characteristics

The concept of a two-step process of cancer development in the oral mucosa, i.e., the initial presence of a precursor subsequently developing into cancer, is well-established. Oral leukoplakia is the best-known precursor lesion. The evidence that oral leukoplakias are pre-malignant is mainly derived from follow-up studies showing that between < 1 and 18% of oral pre-malignant lesions will develop into oral cancer; it has been shown that certain clinical sub-types of leukoplakia are at a higher risk for malignant transformation than others. The presence of epithelial dysplasia may be even more important in predicting malignant development than the clinical characteristics. Three major problems, however, are attached to the importance of epithelial dysplasia in predicting malignant development: (1) The diagnosis is essentially subjective, (2) it seems that not all lesions exhibiting dysplasia will eventually become malignant and some may even regress, and (3) carcinoma can develop from lesions in which epithelial dysplasia was not diagnosed in previous biopsies. There is, therefore, a substantial need to improve the histologic assessment of epithelial dysplasia or, since epithelial dysplasia does not seem to be invariably associated with or even a necessary prerequisite for malignant development, it may be necessary to develop other methods for predicting the malignant potential of pre-malignant lesions. As a consequence of these problems, numerous attempts have been made to relate biological characteristics to the malignant potential of leukoplakias. Molecular biological markers have been suggested to be of value in the diagnosis and prognostic evaluation of leukoplakias. Markers of epithelial differentiation and, more recently, genomic markers could potentially be good candidates for improving the prognostic evaluation of precursors of oral cancer. As yet, one or a panel of molecular markers has not been determined that allows for a prognostic prediction of oral pre-cancer which is any more reliable than dysplasia recording. However, these new markers could be considered complementary to conventional prognostic evaluation.

Progress in determining the malignant potential of oral lesions

The dilemma in managing patients with potentially malignant oral lesions and field change is of deciding which mucosal lesions or areas will progress to carcinoma. Although dysplasia may be predictive, this is not invariable, and there can be considerable inter- and intraexaminer variation in that diagnosis. Recent data on molecular and DNA changes in potentially malignant lesions suggest that it is now feasible to identify those lesions that are truly potentially malignant.

Comparative molecular and histological grading of epithelial dysplasia of the oral cavity and the oropharynx

Histological grading of epithelial dysplasia in the oral cavity and oropharynx is used to predict the risk for cancer and to determine the treatment strategy. This grading, however, is subjective and not well reproducible. Recent publications have shown that molecular markers are promising in cancer risk assessment. The aim of the present study was to compare classical histological and molecular grading and to relate these to the proliferation rate by quantitative assessment of Ki-67 staining. Forty-three samples were analysed from the margins of patients who had undergone resection of their squamous cell carcinoma in the oral cavity/oropharynx. Three experienced pathologists performed the histological grading. With the consensus score, 12 samples were classified as normal and 31 as dysplastic (21 mild, six moderate, and four severe). Loss of heterozygosity (LOH) was assessed in the same samples with 15 microsatellite markers at chromosomes 3p, 9p, 17p, 8p, 13q, and 18q, and was present in 28 of the 43 samples. Twenty-four of the 28 cases (86%) with LOH were classified as dysplastic and four as normal. All ten samples with moderate and severe dysplasia and 14 of 21 samples with mild dysplasia contained LOH. In four of 12 biopsies classified as normal, LOH was found. A very striking and significant difference of the Ki-67 index was observed between LOH-positive and LOH-negative cases, 36.6 +/- 11.1% versus 19.4 +/- 2.8% positive cells, respectively. In mild dysplasia, 13 of 14 lesions containing LOH had a higher Ki-67 index than all seven lesions without LOH. Thus, in the oral cavity/oropharynx, LOH is more frequently found in the histologically higher-grade lesions (moderate dysplasia or worse) and in the lower grade lesions when a high proliferation rate is present. Assessment of proliferation with Ki-67 is a better surrogate for LOH than histological grading.

Oral mucosal dysplastic lesions and early squamous cell carcinomas: underdiagnosis from incisional biopsy

OBJECTIVES

To evaluate the degree and causes of underdiagnosis of incisional biopsy in oral potentially malignant lesions (PML).

DESIGN

Cross-sectional retrospective study.

MATERIALS AND METHODS

All pathology slides (incisional biopsy and resection specimen) from 46 patients with oral PML were reviewed and scored blind. The provisional diagnosis was considered in order to provide underdiagnosis or overdiagnosis according to whether this score was lower or higher than the final diagnosis.

MAIN OUTCOME MEASURES

Concordance between the scores for provisional and final diagnoses was compared for reviewed and unreviewed assessments.

RESULTS

Upon review, underdiagnosis significantly decreased from 23.9% to 4.4% (P=0.016, chi-square with the Yates' correction). As the underdiagnosis ratio was not significantly influenced by intra- or inter-observer variability, it is likely to be related to pathologists' interpretation difficulties when examining incisional biopsy specimens.

CONCLUSIONS

The good quality of incisional biopsy samples was demonstrated, but clinicians should be conscious of the possible underdiagnosis by incisional biopsy when planning therapy in suspected early oral squamous cell carcinoma lesions.